Which ones? The old C500, the newer C800, the C16x family the XC16x or TriCore?
For real time applications needing best inerrupt performance the Infineon micros are great. However Infineon has a very strong focus on automotive so that hobbyists are mostly left behind.
Have used them (except TriCore) in the past, very good micros but a little pricy. Would now rather use ARM7 than C16x. Knowing the interrupt performance of the ARM7 is not as good but in most cases sufficient, many companies compete in the ARM market and as a result they are very good priced micros from e.g. Philips and Atmel.
Summary, good micros from Infineon, tough to beat if maximum real time performance is needed but tool support especially for TriCore is rather limited.
Bob